Comparative study on vegetative,reproductive and qualitative traits of seven diploid and tetraploid watermelon lines

Seven tetraploid watermelon lines developed by colchicine treatments were compared with their diploid counterpart for plant, flower, fruit, seed and qualitative characteristics. Tetraploid genotypes attained statistically higher vine thickness (8.04 mm), leaf area (298.9 cm²) and chlorophyll content (55.6) while internode length and chlorophyll fluorescence was similar to their corresponding diploid. Both pistillate and staminate flower organs (pedicel, anther, ovary, stigma, petals) were larger in tetraploid plants; however, the percent increase in flower components varied across the tetraploid lines. Fruit weight and total sugar content (^∘Brix) in both ploidy fruits was similar. Rind thickness in fruits varied significantly and averaged 12.7 and 17.2 mm in diploid and tetraploid fruits, respectively. Tetraploid genotypes showed sterility, yielded lower number of seed per fruit (37.9), and tetraploid seed was larger and thicker than diploid seed. Overall β-carotene (0.89), lycopene (1.16), fructose (5.43%) and glucose (2.38%) contents were higher in tetraploid than diploid fruits.     

Influence of flower and flowering characteristics on seed yield in diploid and tetraploid red clover

Tetraploid red clover (Trifolium pratense L.) often produces insufficient seed to be economically interesting. Numerous studies have identified poor pollination due to long corolla tubes as its cause, but other studies disagree. Therefore, we investigated seed yield, corolla tube length and flowering traits in 244 plants from five diploid and five tetraploid cultivars during 2 years. Tetraploids produced fewer seeds, fewer flower heads and fewer seeds per head, but an equal number of flowers per head when compared to diploids. Although corolla tubes were longer in tetraploid than in diploid red clover (P < 0.001), no correlation between corolla tube length and seed yield was detected. Therefore, the corolla tube length is likely neither the main nor only cause of low seed yield in tetraploid red clover. Instead, three putative causes for low seed yield were identified: tetraploids produced less inflorescences per plant, possessed a lower degree of determinacy and had markedly less seeds per head when compared to diploids. Possible causes for such differences include lower pollen viability and higher rates of embryo abortion.     

不结球白菜同源四倍体苏州青的诱导鉴定

为获得高产优质的不结球白菜四倍体苏州青,本研究使用浓度分别为0.1%,0.2%及0.3%的秋水仙素溶液,点滴处理二倍体苏州青幼苗植株的子叶生长点,进行5次处理后,通过形态学和细胞学方法筛选鉴定四倍体苏州青植株,并比较二、四倍体苏州青的农艺性状及品质差异。结果表明：秋水仙素浓度为0.2%时加倍效果最好。形态解剖学鉴定结果表明：四倍体在株型、叶片、花、种荚、种子大小都有较明显的变大趋势;四倍体植株叶片气孔较二倍体变大,气孔密度变小;同时四倍体植株花粉粒比二倍体更膨大,更不规则;细胞学鉴定结果表示,四倍体植株染色体数为40条,二倍体植株为20条;通过流式细胞仪鉴定,四倍体植株荧光强度约为二倍体的2倍。通过品质比较分析,结果显示四倍体苏州青的各项生理指标含量较于二倍体均有不同。通过农艺性状比较,单株质量、叶宽、叶厚都有一定程度的增加。本研究利用秋水仙素操作技术,抑制有丝分裂后期纺锤丝的形成,实现染色体加倍,创制不结球白菜新种质,为选育四倍体不结球白菜提供理论基础和种质资源。     

Identification of tetraploid regenerants from cotyledons of diploid watermelon cultured in vitro

Summary Adventitious shoots were obtained from the diploid watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] cultivars Dixielee, Jubilee II, Mickylee, Minilee, and Royal Sweet by culturing excised cotyledons on shoot regeneration medium for six weeks. Tetraploid and diploid regenerants were identified by counting the number of chloroplasts per guard cell pair from leaves of regenerated plants. Cross fertilization of putative tetraploids with diploid pollinators and the production of triploid seed confirmed the efficacy of this approach. The mean number of chloroplasts for tetraploid regenerants was 19.1 whereas diploids averaged 11.2. These values were similar to tetraploid and diploid plants from seed. Ovary diameter, petal, and anther diameter of male flowers, and leaf length by width ratio were also good indicators of plant ploidy. Progeny obtained from self-fertile tetraploids of Mickylee were crossed with various diploid pollinators to produce triploid hybrid seed. All triploid plants from tissue culture-derived tetraploids produced fruit comparable in quality to fruit produced by currently-available triploid hybrids, demonstrating that in vitro tetraploid induction can be used to produce high quality tetraploid plants for use in triploid hybrid seed production.     

Induction of <Emphasis Type="Italic">Anthurium andraeanum</Emphasis> “Arizona” tetraploid by colchicine in vitro

Tetraploids plants of Anthurium andraeanum “Arizona” were successfully induced after treating diploid tissue masses with colchicine. Masses originating from diploid aerial roots were treated with colchicine at three different concentrations (i.e., 0.1, 0.2, 0.3%) for about 3, 5 and 7 h, and then were transferred into Murashige and Skoog medium containing 3 mg/l BAP + 0.2 mg/l 2,4-D. After 60 days, the survival rate and numbers of regenerative shoots were scored. The high concentration and longer duration sharply reduced survival rate. In contrast, the regeneration of plantlets was not noticeably affected by colchicine. Tetraploid plants were obtained in all treatments, but the percentage of induced tetraploids ranged from 0.2 to 7.6%. The best induction was obtained with a 5-h, treatment with 0.3% colchicine. The stomatal size of tetraploid plants was larger than in diploid plants; however, the stomatal density was lower than in diploid plants. Tetraploid plants possessed stronger petioles, thicker and deeper green leaves, and thicker and longer lived spathes in comparison with diploid plants. Abnormal spathes, such as double spathes or those lacking pedicels, were observed in tetraploid plants. Tetraploid plantlets could be regenerated via aerial roots; this technique could be applied to tetraploid plant propagation.     

Amiprophosmethyl-induced efficient in vitro production of polyploids in raphanobrassica with the aid of aminoethoxyvinylglycine (AVG) in the culture medium

Optimum conditions for obtaining tetraploid were investigated in raphanobrassica, the intergeneric hybrid between radish (Raphanus sativus) and kale (Brassica oleracea var. acephala) by treating in vitro plants with an anti-mitotic agent, amiprophosmethyl (APM). Initially, no tetraploids but hexaploids and octaploids were induced by the treatments. Although the leaves of these polyploids of raphanobrassica showed chlorosis during subcultures in in vitro conditions, the chlorosis could be successfully prevented by the ethylene inhibitors, both AVG and AgNO₃. Based on this result, AVG was added into medium used for the culture after the chromosome doubling treatment, which subsequently resulted in increased survival rates of the treated plant materials as well as increased production rates of polyploids including tetraploid. These polyploid plants showed obviously different characters from the original diploid plant. The tetraploid plant had bigger sizes in shoot, flower and leaf, and more number of leaves than the diploid. On the other hand, the hexaploid and octaploid plants had smaller sizes in shoots and leaves, and less number of leaves than the diploid. Concentration of glucosinolates, functional substances of Brassicaceae crops, did not significantly differ between diploid and tetraploid of raphanobrassica, but reduced in hexaploid and octaploid.     

不同倍性栝楼生长发育及果实糖酸含量的研究

摘要：以天然二倍体和人工诱变成的四倍体栝楼为材料,对其生长发育和果实中总糖和总酸含量的测定研究表明：四倍体栝楼的长势快于二倍体;叶片中叶绿素含量明显高于二倍体;四倍体栝楼果实大小、重量、结实率和百粒重明显小于二倍体;果实中总糖和总酸的含量四倍体明显高于二倍体。由DPS软件分析可知：在0.05水平下,四倍体和二倍体栝楼总糖和总酸的含量有显著的差异;在0.01水平下,总糖和总酸的含量有极显著的差异。     

Tetraploid Westerwolths ryegrass

Summary Germinated seeds of the annual Westerwolths ryegrass were treated with colchicine-solutions of 0.05 to 0.4% at a temperature of 29°C in order to obtain autotetraploids. The best results were obtained after treatment for 2 hours with 0.1 and 0.2% solutions or 4 hours with 0.05%. By these procedures about 8% of the treated seeds produced mixoploid or tetraploid mature plants. A preliminary progeny test was performed with seed of outstanding C₁-plants.In spaced plants and in drilled rows the dry matter production of these C₂-families was on average equally as high as that of the most productive original diploid variety. The proportion of leaves was higher in both the first and in the second cut, while drought resistance was considerably better. The tetraploids came later into ear, tillering ability was smaller and mildew attack was slightly heavier. In samples from drilled and from space-planted rows seed production per inflorescence was found to be higher in the tetraploids than in the diploids. The seed of the tetraploids was larger.From the data available it is concluded that chromosome doubling offers favourable possibilities for the improvement of Westerwolths ryegrass. Some suggestions for a breeding programme are given.     

Bilateral polyploidization inDactylis glomerata L. subsp.lusitanica: occurrence,morphological and genetic characteristics of first polyploids

Summary InDactylis glomerata L. subsp.lusitanica, triploid and tetraploid plants were obtained by bilateral sexual polyploidization in crosses between diploid parents known to produce 2n gametes. The polyploid and diploid progeny were compared for allozyme diversity (allele number and heterozygosity), phenological (pollen fertility, inflorescence emergence date), cellular (stomatic cell size) and morphological characters (vegetative biomass, seed weight, total seed number per plant, panicle number and seed number per panicle length) in four contrasting growing conditions. Stomatal cell size and the total number of alleles were significantly lower in diploids than in polyploids which sometimes recovered more than two distinct alleles at a locus via 2n gametes possessing heterozygous loci. Pollen fertility was similar in diploids and tetraploids, but significantly lower in the triploids. Seed weight was significantly higher in polyploids, although the average number of seeds per panicle length and the total number of seeds was higher in the diploid sibs. No phenological differences occurred among ploidy levels whereas such differences were observed inDactylis in all the natural areas of sympatry between diploids and their related polyploids. Our results provide evidence for an instantaneous effect of polyploidization on certain traits and suggest that natural selection would act subsequently on several other traits to allow the establishment of new polyploids.     

Artificially induced polyploidization in Humulus lupulus L. and its effect on morphological and chemical traits

Chemically induced polyploids were obtained by the colchicine treatment of shoot tips of Humulus lupulus L. ‘Sybilla’. Flow cytometry revealed that most of the treatments resulted in the production of tetraploids. The highest number of tetraploids was obtained when explants were immersed in 0.05% colchicine for 48 h. A field experiment was conducted to compare diploid and tetraploid plants and assess the effect of genome polyploidization on the morphological and chemical characteristics. Tetraploids showed significant differences in relation to diploids. They had thinner and shorter shoots. The influence of chromosome doubling was also reflected in the length, width and area of leaves. The length of female flowers in the tetraploids was significantly shorter than that observed in diploids. Tetraploids produced a diverse number of lupuline glands that were almost twice as large as those observed in diploids. The most distinct effect of genome polyploidization was a significant increase in the weight of cones and spindles. Contents of major chemical constituents of hop cones was little affected by ploidy level. Total essential oils were significantly lower than those in diploids. However there was a significant increase in the proportion of humulene, caryophyllene and farnesene, oils desired by the brewing industry.     

Aneuploids of perennial ryegrass (Lolium perenne)

Summary Aneuploid plants of perennial ryegrass (Lolium perenne L.) with 2n=15 to 30 chromosomes were obtained by crossing a near-triploid (2n=3x+1=22) with a diploid or on open-pollination with diploids and tetraploids. Aneuploids occurred with a frequency of 83% in near triploid × diploid progeny and 92% on open-pollination with diploid and tetraploid plants. Aneuploid plants with 15 to 18 chromosomes resembled diploids in morphology and those with 19 to 30 chromosomes were akin to tetraploids. Meiotic studies suggested that most aneuploid plants resulted from transmission of aneuploid egg cells (n=8 to 23). Aneuploid plants with 2n=27 to 30 chromosomes in the progeny of 22×14 cross originated from unreduced egg cells. Plants with 19 to 21 chromosomes were recovered only by immature seed culture. Aneuploid plants with 26 to 30 chromosomes and triploids (2n=21) had higher pollen fertility and bigger seeds than plants with 15 to 22 chromosomes.     

Production of 2n pollen of Asiatic hybrid lilies by nitrous oxide treatment

Tetraploid varieties of lilies have superior agronomic traits such as large flowers and resistance to physiological disorders. In the present study, we attempted to induce 2n pollen of Asiatic hybrid lilies by arresting the meiotic process with nitrous oxide (N₂O) gas. To determine which meiotic stage is optimal for induction of 2n pollen, plants with attached buds at different meiotic stages were treated with N₂O for 24 h in a pressure-tolerant cylinder. A few 2n pollen grains were induced using plants with anthers in prophase I, whereas mixed pollen grains of differing size were produced using plants undergoing meiotic metaphase predominantly in anthers. Although normal lily pollen grains are elliptical, nitrous oxide exposure induced giant pollen grains that appeared spherical. Flow cytometry analysis showed that the giant pollen grains were diploid. When mixed pollen that included normal and giant pollen was crossed to tetraploid cultivars, the resulting seedlings were tetraploid and aneuploid, indicating that the giant pollen grains were diploids that could generate tetraploid seedlings through fusion to diploid eggs supplied from a tetraploid female parent. Thus, treatment with N₂O is useful for the production of 2n lily pollen and may provide a new approach for tetraploid lily breeding.     

Generation and characterisation of colchicine-induced autotetraploid Lavandula angustifolia

Lavandula angustifolia (lavender) is a small woody perennial grown for essential oil, which is steam distilled from flowers. To potentially improve size of flowers and oil yield we produced and characterised autotetraploid plants. L. angustifolia seed germinated in the presence of the mitotic spindle inhibitor colchicine at concentrations of 125 mg l⁻¹ or less resulted in plants carrying sports with larger flowers. Propagation of two sports gave rise to putative polyploid cultivars C3/2 and C6/24. Direct chromosome counts in root tip cells of seedlings from four common cultivars of L. angustifolia and the seed lot from which C3/2 and C6/24 were derived was 50 whereas C3/2 and C6/24 had greater than 90 chromosomes indicating they were autotetraploid. Ploidy level assessed by flow cytometry (FCM) of nuclei showed that 12 cultivars of L. angustifolia had similar nuclear DNA content whereas C3/2 and C6/24 had double the amount of DNA confirming autotetraploidy. The genome size (1C-value) of a diploid L. angustifolia cultivar was estimated by FCM to be 0.90 (±0.07) pg. Morphological characteristics were measured in autotetraploid and control plants. Autotetraploids had thicker peduncles, larger flowers and larger seeds than diploids. Scanning electron microscopy revealed peltate glandular trichomes were larger in the tetraploids relative to diploids. Both tetraploid and diploid cultivars had complex non-glandular trichomes on leaves and sepals and two different types of capitate glandular trichomes were identified on leaves. Autotetraploid lavenders represent useful germplasm both for commercial oil production and future breeding.     

Production of non-chimeral colchiploids in Rubus species by tissue culture

Summary Diploid Rubus allegheniensis Porter and R. rusticanus Merc. shoot tips were proliferated in tissue culture and treated with 0.02 to 0.08% colchicine to induce non-chimeral polyploidy. About 20 shoot tips of each treatment were transferred to test tubes containing modified Anderson's medium for shoot proliferation. Shoots at the 3- or 4-leaf stage were transplanted into Jiffy-7 peat pellets and placed under intermittent mist for rooting. Root tip squashes were made for chromosome counts. Thirteen R. allegheniensis and 7 R. rusticanus plants proved to be autotetraploids (28 chromosomes). Stomata of the autotetraploids were significantly larger than those of the diploids but stomatal conductance of CO₂ and photosynthesis rate were reduced significantly as compared to diploids. Pollen grains in tetraploid were larger than those in diploid R. allegheniensis plants. These results indicate that tissue culture can facilitate the production of non-chimeral colchiploids in Rubus spp.     

Cross compatibility between diploid and tetraploid perennial ryegrass (Lolium perenne L.)

Summary A number of crosses were made between diploid and tetraploid Lolium perenne plants in order to determine the degree of cross compatibility between the two different ploidy levels. The range of hybridization undertaken involved diploidxdiploid, and tetraploid x tetraploid control crossings, diploid x tetraploid crosses, tetraploid x diploid crosses and mixed pollinations. The seed set, the germination capacity of resultant hybrid seeds, and the chromosome constitution of derived seedlings was determined. In addition attempts were made to culture 12 day-old hybrid embryos from the diploid x tetraploid and reciprocal crosses.The crossing results obtained indicated no barrier to fertilization between diploids and tetraploids, but the irregular and poor development of the seed accompanied by much reduced germination, indicated unsatisfactory endosperm establishment of large numbers of triploids, as confirmed by the result of culturing embryos dissected from 12-day old seeds.In preliminary studies undertaken to determine the extent to which diploid and tetraploid ryegrass varieties intercross when grown in close proximity for seed production, Griffiths and Pegler (1966) observed a very low incidence of triploids amongst the progenies of diploid plants exposed to the pollen of tetraploid plants and also amongst the progenies of tetraploid material exposed to the pollen of diploid plants.In these and subsequent studies it was noted that only a very small proportion of the so-called fully formed seeds derived from diploid x tetraploid crosses did actually germinate. When, in 1964, propagules of clones of S.24 perennial ryegrass, well separated from one another, were placed in drills of the tetraploid perennial ryegrass variety Reveille, the proportion of florets which formed caryopses, and of caryopses which germinated was as follows (Table 1).The data (Table 1) clearly indicate that a considerable proportion of the S.24 florets had been fertilized by 2n pollen and had formed caryopses, but most of these had proved to be defective. As noted in the previous studies, the frequency of triploid seedlings was low, thus suggesting incompatibility between the n and 2n gametes for the production of viable zygotes.Of the total progenies classed as tetraploids in the early seedling stage, 80% proved to be ryegrass x tall fescue F₁ hybrids. These arose as a result of free crossing with     

The creation of tetraploid beets

Summary In 1950, 1951 and 1952 germinated seed of various sugar beet and fodder beet strains were treated with colchicine, with the object of obtaining tetraploid plants. The plants were examined cytologically in their first and second year. Only stalks of the C₀ generation (the treated one) in which no diploid cells were found were kept for seed production.By raising the tetraploid C₁ plants in greenhouses the year that the seed has been harvested and by vernalizing the young plants seed production is made annual. For vernalization the plants are kept in a potato storage room cooled by outside air to a temperature of about 5°C and under a day length of 24 hours.The results of the cytological examination demonstrated that collecting seed from tetraploid stalks of the C₀ presents advantages. The C₁ had about 77% tetraploids.It should be noted that the determination of the chromosome numbers of polyploid material is preferable to measurements of stomata or pollen grains as the latter are not reliable.The investigations are being continued. Yield trials with tetraploid material have been made by D. Kloen.     

Main Factors Affecting Cucumber (Cucumis sativus L.) Haploid Embryo Development and Haploid Plant Characteristics

This report gives the first detailed analysis of cucumber haploid plants and the first evaluation of genotype and season effects on haploid embryo development. Female flowers of four F1 varieties and two inbred lines were pollinated with 300 Gy-treated pollen and three-week old embryos were cultured in vitro on E20A medium. The variety ‘Polan’ produced the greatest number of embryos (1.34 per 100 seeds), 51 % of which were capable of further development. The number of embryos able to develop was four times higher in summer than in spring. All the plants obtained, except one, were haploids or aneuhaploids. Haploid plants grew slowly and were sterile, although they occasionally set seedless fruits. The length of the stems, leaves and guard cells was smaller than those of diploids.     

大花香石竹多倍体育种研究

对102个大花香石竹品种的染色体倍性进行鉴定,二倍体、三倍体和四倍体品种分别占77%、6%和17%,当前生产上的主栽品种马斯特、达拉斯和卡曼（具有大花苞性状）都是二倍体品种,71%的四倍体品种为花边复色类型。初步认为部分香石竹四倍体栽培品种是远缘杂交的后代。通过用秋水仙碱处理香石竹品种马斯特的试管苗,获得两株四倍体植株,其花蕾直径增大,而节间变短。     

Seed size in the cultivated potatoes

The three main groups of cultivated potatoes were studied (diploids (2n=24), Andigena (2n=48) and Tuberosum (2n=48)). Seed weights were measured as mg per 100 seeds. In the tetraploids, but not in the diploids, there is a regression of seed weight on seed number per berry with b=–7 mg per 100 per 100 seed, implying nutritional competition between seeds. This effect accounts for very little variation between samples however. Tetraploid seeds are about 30% larger than diploid seeds but there is much overlap between the two groups; genetic control of seed number appears to be predominantly bi-parental, of seed size predominantly maternal, but there are exceptions. Tuberosum seed is slightly larger than Andigena seed and the difference is attributable to the decline in fertility that occurred during the evolution of the former Group. There is no evidence of increase of seed size correlated with selection for plant vigour; experiments with sieved seed of different size grades showed that genetic differences independent of seed size overwhelmingly controlled plant vigour but that there was a transient maternal effect of seed size apparent in the young seedlings and disappearing later in life. General conclusions are: that seed size in the cultivated potatoes is determined by ploidy, by genetic factors (mostly maternal) and by maternal nutritional effects; and that it offers no correlations with plant characters that might be useful to the plant breeder.     

Cytology and digoxin production in hybrids between Digitalis lanata and D. grandiflora

Summary Digitalis lanata is the only commercial source of the cardiac glycoside digoxin. It is an outbreeder and displays considerable variation. An attempt to increase uniformity was made by making D. lanata × D. grandiflora diploid hybrids and from these produce allotetraploid hybrids using colchicine treatment. Such tetraploid plants would be homozygous. Tetraploid hybrids were shown to contain digoxin but at lower levels than in D. lanata. Progeny of selfed tetraploid hybrids were significantly more uniform than D. lanata grown from commercial seed, but were considerably less vigorous.